1. Field of the Invention
The present invention relates to an A/D conversion device including an A/D converter.
2. Description of the Related Art
An input range of the A/D converter, i.e., a voltage allowable range of the input voltage be supplied to the A/D converter is determined with the specification of the A/D converter. Therefore, when the input signal (i.e., the input voltage signal) having a voltage range greater than the input range is subjected to the A/D conversion, it is required to lower the voltage value of the input signal into the input range of the A/D converter.
Thus, there has been suggested an A/D conversion device comprising a resistance voltage-dividing circuit provided at the front of the A/D converter so as to voltage-divide the voltage value of the input signal with two resistors to lower its voltage value (e.g., Japanese Patent Application Kokai No. H09-83365), in order to compress a voltage range in which a voltage value of the input signal varies within the input range of the A/D converter.